Novel 1,2,4-oxadiazole derivatives

ABSTRACT

A NOVEL SERIES OF 1,2,4-OXADIAZOLE DERIVATIVES USEFUL IN THE WHITENING, BRIGHTENING AND/OR BLEACHING OF VARIOUS SYNTHETIC MATERIALS, SUCH AS TEXTILE FIBERS.

United States Patent 3,793,340 NOVEL 1,2,4-OXADIAZOLE DERIVATIVES Asim Kumar Sarkar, Vlaardigen, Netherlands, assignor to Hickson & Welch Limited, Castleford, Yorkshire, England No Drawing. Filed Sept. 21, 1970, Ser. No. 74,175 Claims priority, application Great Britain, Sept. 23, 1969,

46,891/ 69 Int. Cl. C07d 85/48 US. Cl. 260-307 D 8 Claims ABSTRACT OF THE DISCLOSURE A novel series of 1,2,4-oxadiazole derivatives useful in the whitening, brightening and/ or bleaching of various synthetic materials, such as textile fibers.

This invention is concerned with new chemical compounds of use in the whitening, brightening and/or bleaching of polyamide, polyester, polyolefin, acrylic and other synthetic materials in the form for example of textile yarns and fibres, synthetic resin sheets and the like.

Optical whitening agents have in recent years found extensive use in the treatment of textile yarns and fibres, both in their preparation and during washing, and are designed in general to counteract the yellow or otf-White color which white textiles may develop. Such optical Whitening agents also tend to improve colored textiles as they impart a general brightness to them.

The present invention is based upon the discovery of certain 1,2,4-oxadiazole derivatives which have particularly advantageous properties in the whitening, brightening and/or bleaching of textile fibres.

According to one feature of the present invention, there are provided compounds of the general formula:

Ar represents a substituted or unsubstituted benzene or naphthalene ring fused to the oxazole ring; Y represents an alkyl or alkoxy group or a halogen atom;

N represents 0, 1 or 2;

R represents a substituted or unsubstituted alkyl or aryl group; and

X! represents a group of formula -CH=-,

Where X represents a group of formula CH-=CH- the compounds of Formula I may exist in either cisor trans-forms.

According to a further feature of the present invention, there are provided compositions for use in the treatment of an at least in part synthetic textile material comprising at least one compound of Formula I as hereinbefore defined together with a solid or liquid carrier.

According to a still further feature of the present invention, there is provided textile material which is at least in part synthetic having at least one compound of Formula I as hereinbefore defined in association therewith.

The compounds according to the invention have especially advantageous properties in the whitening, brightening and/or bleaching of textile yarns and fibres, in particular, synthetic textile fibres (e.g. polyamide, polyolefin, acrylic and more especially polyester fibers).

alkyl, cyclo- Ice The compounds according to the invention may also, if desired, be incorporated into synthetic melts e.g. of polyester resin which may subsequently be formed into textile yarns and fibres or other shaped articles such as for example synthetic resin sheets and fibres. Where for example textile yarns and fibres are to be formed, the compounds according to the invention may be incorporated into a synthetic resin melt e.g. a polyester resin melt, and the melt then extruded to form the yarns or fibres.

The compounds according to the invention in general have a desirable blue fluorescence, have good light fastness and have good stability to chlorine-containing and oxygen bleach baths. In addition, they in general show a high degree of thermal stability and may thus be used for example in polyester resin melts for the-production of textile yarns and fibres and other shaped articles as described above. They are also of course suitable for use in a more conventional manner, for example in normal dyeing processes e.g. in a dye-bath at elevated temperatures and pressures, or in the pad-bake process. Solutions or dispersions of the compounds according to the invention are convenient in these processes.

In the compounds of Formula I according to the present invention, Ar can for example preferably represent a benzene ring fused to the oxazole ring. The fused benzene or naphthalene ring can, if desired, be substituted by at least one alkyl or alkoxy group each advantageously containing 1 to 6 carbon atoms, e.g.. a methyl or methoxy group. The substituent Ar may also, if desired, be substituted with a halogen atom, for example a chlorine atom. Particularly preferred compounds according to the invention by virtue of their interesting whitening, brightening and/ or bleaching properties are those wherein Ar in conjunction with the oxazole ring forms a S-methyl, 5-methoxy or 5,6-dimethylbenzoxazol-Z-yl group. When Ar represents a naphthyl group it preferably is fused to the oxazole ring via the 1- and 2-positio-ns of the naphthalene ring system.

The substituent Y where present in compounds of Formula I preferably represents an alkyl or alkoxy group which advantageously contains from 1 to 6 carbon atoms or a halogen atom advantageously a fluorine or chlorine atom. The substituent R may, if desired, carry, for example, a halogen substituent and it preferably represents an alkyl group containing from 1 to 6 carbon atoms, advantageously a methyl or chloromethyl group, a cycloal-kyl group containing from 5 to 7 carbon atoms or when it represents an aryl group, a phenyl group.

For the purpose of treating previously-formed textile yarns and fibres in general, the compounds according to the invention may be incorporated into compositions comprising at least one compound of Formula I together with a solid or liquid carrier. Such compositions may for example be adapted for use in the washing of finished polyamide, polyolefin, polyester and acrylic fibres and can take the form of solutions, suspensions and dispersions of compounds of Formula I in appropriate liquid carriers such as water, sulpholane, dimethylforrnamide and dimethylsulphoxide. When dispersions are used they conveniently include dispersing agents such as for example alkyl naphthalene sulphonates. Aqueous compositions may, if desired, also contain, for example, synthetic detergents, soaps or surface active agents. Alternatively the compositions may be in solid form and comprise at least one compound according to the invention together with a solid synthetic detergent or soap as carrier. The compounds of Formula I may be employed in the manufacture of synthetic yarns and fibres, e.g. by addition to compositions from which the fibres are prepared by spinning or extrusion.

The 1,2,4-oxadiazole derivatives of Formula I may for V example be prepared 'byany convenient'method (elgl' of the kind described in Review of Chemistry of 1,2,4- oxadiazoles F. Eloy, Fortsh'r. Chem. Forsch., 1965, 4, 807876) and are advantageously prepared by one of the following processes:

(a) Reaction of an amidoxime of formula N-OH 7 Ya I NH: (II) Yn (III) (wherein Ar, X, Y and n are as hereinbefore defined) with hydroxylamine. However, the amidoximes of Formu- 1a II may also be prepared by the intermediate formation of a thioamide of formula (wherein Ar, X, Y and n are as hereinbefore defined) which may be prepared, for example, by reacting the corresponding nitrile of Formula III with hydrogen sulphide. Methods which may be used for the preparation of amidoximes have been reviewed by F. Eloyin Chemical Reviews.

(b) The oxidative cyclization of a compound of formula OH (V) (wherein Ar, X, Y, n and R as hereinbefore defined). The cyclization may be effected under conventional conditions, for example using a mild oxidizing agent such as oxygen, manganese dioxide, copper acetate, chloranil and the like. The oxidation may conveniently be effected in a solvent which advantageously is inert to the oxidizing conditions. Suitable solvents include, for example halogenated hydrocarbons such as chlorobenzene.

(wherein X, Y, n and R are as hereinbefore defined). 'Ihe 1,2,4-oxadiazoles of Formula VII used asv starting materials for this process may, for example, be prepared by a method analogous to that used for the preparation of the compounds of Formula I according to process (a) above such as the reaction of an amidoxime-with a functional derivative of a carboxylic acid. The various substituents required on the oxadiazole ring of thecompound of Formula VII are advantageously introduced so asto prevent incompatibility of the reagent used to prepare the oxadiazole ring system and any particular groupinthe" compound of Formula VII. Thus, it isadvantageous to prepare compounds of Formula VII by the introduction of the substituent- CHO--X into a pre-formed S-aryl- 1,24-oxadia zole system, for example by dia otizing-a 3 (4 aminophenyl)-- 1,2,4 oxadiazole and coupling with a. suitable reagent such as furfuraldehyde, since the aidehyde group mayitself react with hydroxylamine during formation of the amidoxime. In-the preparation of amidoximes used ration of 1,2,4-oxadiazoles of Formula I-or VII, hydroxyl amine is preferably used in its free form and may conveniently be liberated from a salt thereof which in general is more stable than hydroxylamine itself. Suitable salts include hydroxylamine hydrochloride and sulphate. The following examples, in which all parts are by weight, are given by way of illustration only:

EXAMPLE 1 1-(5,6-dimethylbenzoxazol-Z-yl)-2-[4-(5-methyl-1,2,4-

oxadiazol-3 -yl -phenyl] -ethylene 2-(4-cyanostyryl)-5,6-dimethy1 benzoxazole (6 pts.) was dissolved in butanol (350 pts.) and hot ethanol (150 pts.) was added to this solution. Hydroxylamine hydrochloride (1.7 parts) and 1.3 pts. of sodium carbonate in water (25 pts.) were added to this solution and the mixture refluxed for 24 hrs. At the end of 24 hrs. the mixture was concentrated. to remove most of the solvent and quenched in water (100 pts.). The resulting amidoxime (6.5 pts.) was filtered and dried. M.Pt.270275 C.

The amidoxime obtained above was dissolved in hot glacial acetic acid (75 pts.) and cooled to room temperature. To this solution, acetic anhydride (75 pts.) was added and the mixture slowly heated to reflux. The mix. .ture was refluxed for /2 hr. and the mixture of acetic dried. The solid was. recrystallized frorntoluene. M.Pt.

The 1,2,4-oxadiazoles of Formula V may be prepared by a convenient method, for example, by conventional processes for the formation of amine and azomethine type xmn. 345-356. E12"... 1320 and 1315 r A dilute solution of the compound in alcohol gives blue violet fluorescence.

-2- (4-cyanostyryl)-5,6dimethylbenzoxazole may be prepared by the condensation of 2,5,G-trimethylbenzoxazole EXAMPLE 2 5 [4(5-methyl-1,2,4-oXadiazol-3-yl') phenyl] -'-furfuraldehyde (12.7 pts.) and 2-amino-4,S-dirhethylphehol (6.9

pts.) are refluxed in monochlorobenzene for 1 hours.

for the prepa The water forrnedis removed by azeotropic distillation. At the end of the. reaction, when the required amount of water is removed, '30I'15t's. of manganesedi'oxide (activated) is addedportionwiseover /2 hr.(The mixture is,refluxed fora further 15mins. with goods'tirring'ffiltered hotQan d the residue is washed with hot monochlorohenzene. The combined filtrate is concentrated and evaporated to dryness. The residue, a yellow solid, is slurried in acetone (cold) and filtered, to give 14.5 pts. of the desired compound in crude form. The product is crystallized from Cellos-olve. M.Pt. 225-227 C. A dilute solution of the product in alcohol has blue violet fluorescence.

)unnx, 360 mu. EH1 1330 The starting material used for this example was prepared as follows. 13.9 pts. of hydroxylamine hydrochloride and 16.4 pts. of sodium acetate in 20 pts. of water were added to 114.8 pts. of 4-nitrobenzonitrile in 100 pts. ofi ethanol. The mixture was refluxed for 12 hrs. After 12 hrs. the mixture was poured into 300 pts. of water, cooled, filtered, washed and dried to give 14.4,pts. of amidoxime, M.Pt. 176178 (lit. M.Pt. 179-181" C.).

14.4 pts. of 4-nitrobenzamidoxime was added to a mixture of 25 pts. of glacial'acetic acid and 25 pts. of acetic anhydride, refluxed for 2 hrs. and poured into 200 pts. of water, and boiled for /2 hr., then cooled and filtered to give 14.6,pts. of crude 3-(4-nitrophenyl)-5-methyl-1,2,4- ox-adiazole. M.Pt. 1'36-l38 C.

To a boiling mixture of 40 pts. of sodium sulphide (Na S-9H pts. of sulphur, 1 00 pts. of water and 80' pts. of methanoL. 26 pts. or 3-(4-nitrophenyl) 5- methyl-1,2,4-oxadiazole .were added and the mixture boiled for /2 hr. The mixture was then'poured'into 1000 pts. of water, filtered, washed and dried. Yield 19.5 pts. (M.Pt. 113-114 C.) of 3 (4-aminophenyl)-5 methyl- 1,2,4-oxadiazole. p a I 1 116 pts. of the aminophenyl compound obtained above were dissolved in 300 pts. of acetic acid, cooled to room temperature with stirring and 204pts. of cone. 'HCl in 500 pts. of water were added quickly to the solution and cooled to 0 C. The mixture was diazotized with a solution of sodium nitrite (46 pts. in 200 pts. of water) maintaining the temperature between 0 and 5 C. To the diazonium chloride, a solution of 80 pts. of furfural in 450 pts.,pf acetone was added and the mixture warmed to ;C. A solution of 30 pts. of cupric chloride in 200 pts. of water were added to the mixture and the temperature raised to C. An exothermic reaction took place and the temperature rose to C. (slight coolingused). The mixture was left overnight at this stage. The mixture was then filtered and washed, and the solid recrystallized from ethanol to give 5-[4-(S-methyll-1,2,4-oxadiazol-3-yl)- phenyl]-furfural. M.Pt. 182l83 C.

The following compounds were prepared analogously to the methods described in the above examples, some physical data also being given:

U.V. absorption characteristic M.P., Colorof E 1% Example 0. fluorescence Am. m.

3. N N 0 212214 Blue violet... igi

C-CH=CH C g 0 4 N N 0 217-219 ...-.do

, c oH =cH -c 5 N 219-221 .do 341 1,136

CH N-O c-cn=cn@ c v e o (:1 5

6 N 202-203 ......(10 338 1,836 I N--0 352 1,220 on. 2 OCH-:CH C

( JHaCl "7. N 213-214 .-..-do 355 1, 425 CH CH-H N-0 Y -t l \o i o 8.; 208-211 Violet-Eldon" 359 1,050

EXAMPLE 14 The compound obtained in Example 2, as such or in solution in a suitable solvent, is added to a hot melt of a polyester resin, which is extruded through a spinnerette to form filaments of polyester fibres by melt spinning.

0.1% of the compound (based on the weight of the resin) gives a very good brightening effect. Alternately, a solution obtained by dissolving the same compound in a suittable solvent may be sprayed on to the extruded filament during or after stretching.

The compound may also be incorporated I in other colourless polymeric materials like polyarnides, polyolefins and polyacrylics, and the resins may be in the forms of fibres, films or shaped articles. 1

EXAMPLE 1s .05 part of the compound prepared as described in Example 2 and 1.5 pts. of a polyethylene glycol ether of j EXAMPLE 16 Polyester fibres are introduced into an aqueous liquor containing 1 g. sodium oleyl sulphate, 0.75 g. formic acid and 0.1 g. of the compound of Example 8 per litre at a goods to liquor ratio of :1. The treatment liquor is heated to boiling and maintained at the boiling temperature for mins. The fibres are then rinsed and dried; they exhibit a very good brightening effect. The

compound of Example 8 may be introduced into the dye bath as a dispersion as described in the previous example or as a solution in a suitable solvent like dimethyl formamide.

The above, compounds may also be used with a shading blue or violet dyestutf. They may also be used for brightening polyester-cotton blends in conjunction with known cellulosic brighteners, for example, the triazinylstilbene or other types.

I claim: 1 1

1.; A compound of theformula:

I "st wherein:

Ar is phenyl, naphthalene, or phenyl or naphthalene substituted by halogen or by an alkyl or alkoxy group containing from 1 to 6 carbon atoms, said phenyl or naphthalene being fuzed to the oxazole ring;

Y is a halogen atom or an alkyl or alkoxy group containing from 1 too carbon atoms;

n is 0, 1, or 2;

R is an alkyl group containing from 1 to 6 carbon atoms, a-cycloalkyl group containing from 5 to 7 carbon atoms, a phenyl group, an alkyl group containing from 1 to 6 carbon atoms substituted by a halogen group, a cycloalkylg'roup containing from 5 to 7 carbon atoms substituted by a halogen atom, or a phenyl group substituted by a halogen atom; and

X is

lit

3. A compound as claimed in claim 1 wherein the group is selected from the group consisting of a 5-methyl-, a 5-methoxy-, and a 5,6-dimethyl-benzoxazol-Z-yl group.

4. A compound as claimed in claim 1 wherein Ar represents a naphthylene ring system fused at the 1- and Z-positions to the oxazole ring.

5. A compound as defined in claim 1 which is 2-(5,6 dimethylbenzoxazol-Z-yl)-5-[4-(5-methyl 1,2,4 oxadiazol-3-yl -phenyl] -furan.

6. The compound of claim 1 wherein Ar is phenyl or naphthalene substituted by chlorine.

10 7. The compound of claim 1 wherein Ar is phenyl or naphthalene substituted by a methyl or methoxy group. 8. The compound of claim 1 wherein Y is a chlorine or fluorine atom.

FOREIGN PATENTS 58,961 12/1967 East Germany 260-240 CA JOHN D. RANDOLPH, Primary Examiner US. Cl. X.R.

117-335 R, 33.5 T; 252117, 301.2 WV, 543; 260'-37 NP, 41 C, 75 N, 78 R, 93.7, 240 D, 307 G 

